We have successfully achieved high speed (~50 ns) unipolar operation in RRAM devices comprised of titanium oxynitride (TiON) combined with a control resistor connected in series. For unipolar switching, programming and erasing pulses can be the same width, typically, a few tens of nano-seconds. This enables high speed and high density cross-point RRAM memory arrays. In addition, we demonstrate how switching characteristics can be controlled by a series resistor.